Purification of hydroxymethyl furfural



Aug. 1, 1961 R. E. .JoNEs E-rAL PURIFICATION OF HYDROXYMETHYL FURFURALFiled Jan. l0, 1958 w um m'ZOo .uz-JOU.

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mmmomm INVENTORS ROBERT E. JONES By HENRY B. LANGE pnt/nil, wml, WMM,,5M/1M? 7W ATTORN EYS United States Patent O 2,994,645 PURIFICATIoN oFHYDROXYMETHYL This invention relates to the purification of crudehydroxymethyl `furtural (HMF), and lhas for its object the provision ofan improved distillation process for distilling the crude HMF in goodyield.

In the distillation of crude HMF as practiced heretofore, yields of onlyfrom about 45 to 60% could be obtained due either to decomposition ofthe HMF or to HMP ether formation. The presence of acid in the crudeHM-F leads to objectionably accelerated decomposition. However, even inthe absence of acid, the low yield may also be due to ether formationaccording to the following reaction:

A y i 20H0i HCHrOH--mnoi -iornoorn )CHO-tmc \o o o As shown by thereaction, water is formed and this leads to a non-reproduciblepressure-temperature relationship and to a lowering of the vacuumcapacity of the system. Both of these factors, the presence of acid andether formation, have been deterrents to the successful puriiication ofHMF by distillation.

This invention is based on the discovery that when crude HMP isdistilled in a system that was thoroughly degassed under high vacuum,the crude HMF protected from moisture, and the distillation carried outcontinuously at high temperature and for the shortest practical contacttime, that yields of over 90% of pure HMF are attainable. The process ofthe invention `comprises the initial thorough degassication of thesystem, the maintenance of the crude HMP out of contact with moisturebecause of its highly hygroscopic property, and the continuous supply ofcrude moisture-free HMF to the system to provide `a minimum of contacttime at the distillation temperature while under a very high vacuum.

The accompanying drawing illustrates more or less diagrammatically anarrangement of apparatus suitable for carrying out a process of theinvention.

In carrying out a process of the invention the crude HMF is iirstdegassed under a high vacuum, say 30 microns or less. The degassing andmoisture removal may be done by passing the crude HMF through a steamheated chamber under a vacuum to separate the water vapor and othergases that may be present. The degassed HMP is protected from contactwith moisture and is fed continuously at a controlled rate into adistillation ap'- paratus that is maintained under a high vacuum and ata suitable distillation temperature, for example about 175 C., and forthe shortest possible residence time at the high temperature. Theoperation may be carried out advantageously by passing the HMPcontinuously into a residence vessel which is externally heated at thepreferred temperature of from 150 C. to 200 C.

By controlling with valve V the rate of addition of HMF from thereceiver for degassed HMF to the residence vessel Where distillationtakes place and the rate of removal of vapors the residence time of theliquid HMF at the distillation temperature can be controlled. Theresidence vessel is heated under a vacuum to distill the HMF which ispassed into a condenser for the condensation of the puried HMP. In asmall laboratory operation carried out in -a distillation unit includinga pot or distillation ask of l liter capacity, a condenser, and aPatented Aug. 1, 1961 receiving ask of 2 liters capacity, the crude HMFwas passed into t-he distillation flask at the rate of 2 kg. per' day.The results of this operation are listed in Table 1.

Table I N o. Crude Pot Press., Vap. Dist. Percenty t., g. T C. mier. T.,C. Wt., g. Yield Total 15, 178. 0 175 13, 199. 8 87. 2

The contact or residence time can vary from a very/y short time, say,about one second, to a few minutes, for. example upto 20 minutes,depending on the rate of addi tion and distillation. One can put the HMFthrough asl fast as desired, as only the percent distillation per passisi influenced. This relationship is shown in Table II in. which theyields are Weight yields per pass and have not: been corrected for inert(non U.V.bearing) materials..

The run 36B was a second pass distillation of 35 result'-v ing in atotal weight recovery of 70%. When this is cor-- rected for inertmaterials, the U.V. yield is -about U.V. yields of up to 96% arepossible of attainment by the process of the invention. The distillationresults were made on distillations carried out in an ASCO 50 Rota-filmLaboratory Still which apparatus is referred to in a catalog entitledHigh Vacuum `and Molecular Distillation with the Rota-film Still, ArthurF. Smith Company, 311 Alexander Street, Rochester 4, N Y.

Table Il Feed Wt. Est. Rate, Run Est. Press. Jacket Per- Rest- Run No.g. per Tune Hold- (mm.) Temp., cent dence min. (min.) up (g.) C. YieldTime (Min.)

21. 6 57 60 0. 830 189 10. 9 1. 4 20. 1 160 93 2. 50 199 18. 0 1. 5 19.2 54 13 1.00 204 21. 6 1. 6 14.1 3l 1. 00 177 30. 5 2. 1 15. 0 35 31 1.69 197 25. 7 2. 0 12. 5 79 32 3. 34 200 32. 2 2. 4 10. 8 59 24 0. 64 19048. 0 2. 8 8. 9 90 23 0. 77 187 45. 0 3. 4 8. 9 105 17 1.38 192 58. 9 3.4 10. 5 100 71 2. 84 195 42. 9 2. 9 2. 5 116 8 0. 77 112 61.3 12. 0 2. 542 11 0. 99 114 51. 4 12. 0v 3. 0 105 16 0. 72 113 56. 3 10. (l: 3. 5102 19 0. 19 34. 4 8. 61 3. 0 118 9 0. 24 45. l 10. 0- 8. 4 108 32 0. 57123 27.8 3. 61 5. 1 54 4 0. 43 132 41.0 5. 9 19. 8 33 50 75. 00 183 8. 4l. 5l

I claim:

1. The process for purifying crude hydroxymethyl ful'fural whichcomprises lremoving initially from the crude hydroxymethyl furfuralgases and water by heating under a high vacuum, heating the degassed andmoisture free hydroxymethyl furfural to distillation temperature in adistillation vessel while under a high vacuum of from 0.19 to 3.34 mm.,and controlling the continuous addition of liquid hydroxymethyl furfuralto the vessel and the rate of vapor removal therefrom to maintain ashort residence time for liquid hydroxymethyl furfural in the vessel.

2. The process for purifying crude hydroxymethyl furfural whichcomprises initially and thoroughly removing from the crude hydroxymethylfurfural gases and water by heating under a high vacuum, heating thedegassed and moisture free hydroxymethyl furfural to distillationtemperature in a distillation vessel in the substantial ab sence ofwater vapor While under a high vacuum of from.l 0.19 to 3.34 mm., andcontrolling the continuous addition of liquid hydroxymethyl furfural tothe vessel and the rate Qf Vapor removal therefrom to maintain aresidence time 2,210,926 Hichman Agg. 13, 1940 in the vessel of from 1s'ec'ond t 20 rin-t'es'. 16092337 Taylor et al Sept. 2', 19'52References Cited in the le of this patent OTHER REFERENCES UNITED STATESPATENTS 5 Recueil Travaux Chimiques des Pays-Bas (1919),

2,136,774 Hichman Nov. 15, 1938v V01. 38. (Copy in Sientic Library.)

1. THE PROCESS FOR PURIFYING CRUDE HYDROXYMETHYL FURFURAL WHICHCOMPRISES REMOVING INITIALLY FROM THE CRUDE HYDROXYMETHYL FURFURAL GASESAND WATER BY HEATING UNDER A HIGH VACUUM, HEATING THE DEGASSED ANDMOISTURE FREE HYDROXYMETHYL FURFURAL TO DISTILLATION TEMPERATURE IN ADISTILLATION VESSEL WHILE UNDER A HIGH VACUUM OF FROM 0.19 TO 3.34 MM.,AND CONTROLLING THE CONTINUOUS ADDITION OF LIQUID HYDROXYMETHYL FURFURALTO THE VESSEL AND THE RATE OF VAPOR REMOVAL THEREFROM TO MAINTAIN ASHORT RESIDENCE TIME FOR LIQUID HYDROXYMETHYL FURFURAL IN THE VESSEL.